export default {
  namespaced: true,
  state:() => ({
    // 购物车的数组，用来存储购物车中每个商品的信息对象
        // 每个商品的信息对象，都包含如下 6 个属性：
        // { goods_id, goods_name, goods_price, goods_count, goods_small_logo, goods_state }
    cart: JSON.parse(uni.getStorageSync('cart') || '[]')
  }),
  mutations: {
    addToCart (state, goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      if (!findResult) {
        state.cart.push(goods)
      } else {
        findResult.goods_count++
      }
      // 通过 commit 方法，调用 m_cart 命名空间下的 saveToStorage 方法
         this.commit('m_cart/saveToStorage')
    },
    saveToStorage(state) {
      uni.setStorageSync('cart', JSON.stringify(state.cart))
    },
    // 更新复选框的状态
    updataGoodsState (state, goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      if (findResult) {
        findResult.goods_state = goods.goods_state
        // 数据持久化
        this.commit('m_cart/saveToStorage')
      }
    },
    // 更新商品数量
    updataGoodsCount (state, goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      if (findResult) {
        findResult.goods_count = goods.goods_count
        // 数据持久化
        this.commit('m_cart/saveToStorage')
      }
    },
    // 删除商品
    removeGoodsById(state, goods) {
     state.cart = state.cart.filter(x => x.goods_id !== goods.goods_id)
     // 数据持久化
     this.commit('m_cart/saveToStorage')
    },
    // 更新购物车中所有商品的勾选状态
    updataAllGoodsState(state, newState) {
      state.cart.forEach(x => x.goods_state = newState)
      // 数据持久化
      this.commit('m_cart/saveToStorage')
    }
  },
  getters: {
    // 购物车中所有的商品数量
    total(state) {
      // let c = 0
      // state.cart.forEach(x => c += x.goods_count)
      // return c
      return state.cart.reduce((total, item) => total += item.goods_count, 0)
    },
    // 已勾选商品
    checkedCount(state) {
     return state.cart.filter(x => x.goods_state).reduce((total, item) => total += item.goods_count, 0)
    },
    // 已勾选商品的总价格
    checkedGoodsAmount(state) {
      return state.cart.filter(x => x.goods_state).reduce((total, item) => total += item.goods_count * item.goods_price, 0).toFixed(2)
    }
  }
}
